Patient support apparatuses, such as hospital beds often allow rotation of patient support surfaces in different positions to achieve a plurality of configurations for the bed. Many hospital beds have an elevation system which can raise and lower the frame of the patient support surface. Often, these elevation systems are electrically powered. Examples of configurations for the bed include a lying (sleeping) position, a vascular position with the legs of the patient being maintained horizontal and a raised (sitting) position.
Cardiopulmonary resuscitation (CPR) is an emergency procedure performed to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest. It is indicated for those who are unresponsive with no breathing or abnormal breathing. Cardiac arrest is a medical emergency that is potentially reversible if treated early. Unexpected cardiac arrest can lead to death within minutes. A CPR handle is typically provided on hospital beds to speed up the process of lowering the head section and flattening all sleep surface sections to allow medical personnel to begin CPR procedures. This is especially useful if the head section of the bed is in the fully raised configuration.
The movements of the sections of hospital beds are usually slow so as not to disturb the patient. Rising and lowering the head section typically take 25 to 35 seconds, and noise and jolts are avoided to the extent possible. In an emergency situation, time is of the essence. It is therefore acceptable to lower the head section in 5 seconds in that situation.
Some actuators available on the market are disengageable. When gears are disengaged, the time of descent with a heavy patient is less than 2 seconds. This is considered too rapid according to medical personnel who fear discomfort or injury for themselves or the patient. Furthermore, safety regulations require that all movement be attended, meaning that medical personnel has to hold a handle during the process, letting go would stop the displacement right away. The actuator is therefore often mounted in parallel or in series with a damper. The combined system slows down the emergency descent to a 5 second duration. A gas spring can further assist the actuator by reducing the effort required by the actuator for rising the head section with a patient present on the bed.
In the event that the CPR handle is released before the head section is fully horizontal and resting on the frame, there is a considerable effort transmitted to the actuator gears. As a result, the gears can get stripped, the shaft can break and the actuator may need to be replaced. If this occurs, the patient would then need to be transferred to another bed.
Some dampers have an integrated spring which can act as a two-step force to reduce speed when almost compressed. The major drawback of this solution is that the actuator has to pull its way in to its minimum length. Most of the actuators have half the force in pull compared to push action. Depending on the strength of the spring, this action may deteriorate the actuator in the long run.
Medical staff sometimes need to place a patient in the vascular position to help with blood circulation. The vascular position of the bed frame is obtained by orienting the patient support assembly such that the legs of the patient will be vertically higher or at the same level than the patient's heart. The foot rest is parallel to the ground in this position. This is typically achieved by raising the thigh section first which is usually power activated. The foot end of the bed is then manually raised by the medical staff using a pop rod which rises the foot rest upwards. The thigh section is usually power activated to raise it to an angle while pushing the thigh rest towards the upper body of the patient. The headrest of the bed is typically lowered afterwards to reduce the vertical height of the patient's heart and achieve a full vascular position.
Because the pop rod is manually operated, the patient can experience jolts. Furthermore, there is a risk of injury to the medical staff during the manual operation. Finally, the process has two manual steps which tend to take some time. This tends to delay placement of the patient in the appropriate position. Often, medical personnel do not want to use a manual system that requires forcing against the patient weight. Furthermore, the system is usually hidden under the sleep surface foot section and is sometimes unknown to them.
When a patient is taller than average, the bed can be extended to accommodate his height. There are several ways to extend a bed to accommodate a taller patient. In some prior art beds, the footboard is removed and an added accessory is attached at the location freed by the removal of the footboard. The footboard is sometimes stored but can alternatively be re-attached to the added extension to continue use of the controls on the user interface. Some prior art systems lengthen the frame and add a pad to level the extended surface with the mattress top. When the sleep surface is angled or raised in a vascular position, the bolster remains on the frame. In other prior art beds, the extension is part of the foot section of the bed. It may be manually or power mechanically extended. Usually, the extension is stored above or under the lower body surface and is pulled away from the upper body surface in use, the lower body surface and the extension at least partially overlapping in the retracted position. The footboard is typically provided on the extension.
Medical staff sometimes need to pull back the patient towards the head end of the bed after having raised the upper body surface of the bed from the flat lying position to a raised seated position. This is caused by the movement of the patient towards the foot of the bed during rotation. This can cause injuries in medical personnel and discomfort for the patient.
Example prior art hospital beds are described in US Patent Application Publication Nos. US 20140115785, US 20130145550, US 20130333115, US 20140013512, US 20100122415, US 20120005832 and in U.S. Pat. Nos. 7,441,291, 6,496,993, 6,968,584, 6,336,235, 5,682,631, 5,906,017, 6,640,360, 7,849,539, 8,555,438.